Pneumatic systems often include one or more compressors that can experience surge events in which pressure associated with the load may rapidly increase. At least some aircraft engines are typically started with the assistance of an auxilliary power unit (APU). The APU provides the aircraft with electrical and pneumatic power. Pressurized air from the APU load compressor is routed to an aircraft engine via a duct system where the pressurized air drives a turbine at the engine to generate power and rotation on the engine shaft for engine start. If the aircraft engine, or other pneumatic load, stops utilizing the pressurized air, then the potential exists for a surge condition in which the pressure within the duct increases back to the APU. Conventionally, a surge valve is integrated into the APU to prevent surge conditions. However, the surge valve may take more time than is desirable to open. Because the surge valve is physically located within or at the APU, if the surge valve does not respond quickly enough, then the surge condition may reach the compressor before the integrated surge protection valve can open.
Surge protection within APUs is typically designed for a particular aircraft and engine platform. If components within that aircraft or engine system are modified, the surge protection may not be adequate. For example, if an aircraft is upgraded with new engines that have different starting and operating specifications than the engines for which the APU was originally utilized, then the surge protection that is integrated with the APU may not be adequate. Redesigning or replacing the APU within an aircraft to accommodate engine or other aircraft component changes may be costly and time consuming.
It is with respect to these considerations and others that the disclosure made herein is presented.